Thin film electroluminescent (EL) display panels have been known to be very useful for displaying information in as much as the thin film structure including the cross electrodes can be deposited on a glass substrate thereby providing a matrix display panel capable of being selectively energized to activate individual pixels thereon. One of the problems in the past in the development of EL panels has been developing a high degree resolution (i.e., a high number of electrodes per linear inch), without creating shorts between electrodes after deposition.
Most thin film EL devices have had their electrodes patterned by a wet process known as photolithography. The photolithographic method has been a very attractive method due to its cost effective fabrication of large area circuits containing a high density of components. Photolithography is very similar to processes used to develop photographs in that the deposit to be patterned is coated with light sensitive material, which is then exposed to a negative or positive pattern and then developed and later stripped in various corrosive developing solutions. The disdvantages of this method is that it is slow and labor intensive and involves many steps, each one subject to failure or possible contamination of the thin film device. Additionally, the thin film EL devices are very sensitive to moisture and many of the solutions are aqueous in nature. Furthermore, photolithography produces electrode patterns with sharp edges that have been shown to promote electrical breakdown of the thin film EL devices. A method which would produce a rounding of the electrode structure edge would help to prevent this and would be considered a significant advancement in the electrode structure deposition art.
It is also believed that an apparatus that would assist in the deposition of thin film electrode structures while promoting simplicity and manufacturing ease would constitute a significant advancement in the art.